1. Field of the Invention
The present invention relates in general to current collectors and methods for manufacturing same, and, more particularly to a current collector device wherein an aluminum current collector having a reduced interfacial impedance, relative to other aluminum current collectors, is utilized.
2. The Prior Art
Various types of current collector devices for use in association with solid and/or liquid electrolytes have been known in the art for several years. For example, when used in association with rechargeable lithium batteries, such current collectors have typically been constructed from nickel or aluminum. While both of such materials have proven as functional alternatives in such rechargeable batteries, they do, nonetheless, exhibit several deficiencies.
Specifically, nickel, in addition to its high cost, has a density of 8.90 g/cc. As a result of the use of such a relatively high density current collector, electrodes constructed using such a current collector exhibit a relatively low energy density. Furthermore, as known in the art, nickel oxidizes at a potential above 4 volts versus Li.sup.+ /Li.degree., and therefore, nickel current collectors cannot be used effectively at electrode voltages above that value.
Aluminum, on the other hand, which is quite inexpensive and which has a density of only 2.7 g/cc, eliminates the disadvantages associated with the use of nickel. Unfortunately, current collectors constructed from aluminum exhibit a relatively high interfacial impedance associated to the presence of a thick oxide layer at its surface, which, in turn, results in a loss of energy and reduced power. Indeed, such a loss of energy and power is generally attributable to the fact that aluminum includes a native oxide layer which 1) acts as an insulator, and thus severely limits electrical conductivity, and 2) greatly hinders adhesion of an electrochemically active electrode material which is to be directly, or indirectly applied to the surface of the aluminum current collector.
It is thus an object of the present invention to provide a current collector device and method of manufacturing same, wherein the device so made includes an aluminum current collector having a substantially reduced interfacial impedance and substantially increased adhesive capabilities relative to the prior art.
These and other objects of the present invention will become apparent in light of the present Specification, Claims and Drawings.